Osteogenesis Imperfecta

Definition

Definition of Osteogenesis Imperfecta
Osteogenesis imperfecta is due to a genetic mutation in the gene that directs the body to produce collagen. Osteogenesis imperfecta can either be passed on from a parent who has the disease, or it can occur as a spontaneous mutation in a child. Most cases of osteogenesis imperfecta that are passed from parents are due to a dominant mutation (comes from one parent who has osteogenesis imperfecta), although a small number of cases are due to recessive mutations (comes from a gene from both parents, neither having the disease).

Symptoms

Symptoms of Osteogenesis Imperfecta
Typical problems seen in patients who have osteogenesis imperfecta include bone fragility, short stature, scoliosis, tooth defects, hearing deficits, bluish sclera, and loose ligaments. Osteogenesis imperfecta gets its more common name, brittle bone disease, because these children are often diagnosed after sustaining multiple broken bones.

The symptoms of osteogenesis imperfecta vary greatly between individuals. Some children are diagnosed very early in life, while others can be more challenging to detect the condition. Multiple fractures due to low-energy injuries should raise suspicion of an underlying condition such as osteogenesis imperfecta.

Causes

Causes of Osteogenesis Imperfecta
Osteogenesis imperfecta can also cause weak muscles, brittle teeth, a curved spine and hearing loss. The cause is a gene defect that affects how you make collagen, a protein that helps make bones strong. Usually you inherit the faulty gene from a parent. Sometimes, it is due to a mutation, a random gene change.

Diagnosis

Diagnosis of Osteogenesis Imperfecta
Osteogenesis imperfecta is usually suspected in children whose bones break with very little force. A physical examination may show that the whites of their eyes have a blue tint.

A definitive diagnosis may be made using a skin punch biopsy. Family members may be given a DNA blood test.

If there is a family history of OI, chorionic villus sampling may be done during pregnancy to determine if the baby has the condition. However, because so many different mutations can cause OI, some forms cannot be diagnosed with a genetic test.

Treatment

Treatment of Osteogenesis Imperfecta
Currently, there is no known cure for osteogenesis imperfecta. The primary focus of treatment should be on prevention of injuries and maintaining healthy bones. Ensuring that children with osteogenesis imperfecta eat a nutritious diet, get regular exercise, and maintain a healthy weight is fundamentally important. Often children with osteogenesis imperfecta will require ambulatory aids, braces, or wheelchairs.

Surgical treatment of osteogenesis imperfecta depends on the severity of the condition and the age of the patient. In very young children, many fractures are treated the same, as if the child had no underlying condition. However, surgical stabilization of fractures becomes more common, even at a young age.

The role of medications in the treatment of osteogenesis imperfecta is evolving, but recent studies show a benefit of treatment with bisphosphanates and calcium supplements. The rationale is that these treatments will strengthen the bone and decrease the frequency of fractures. Research is also being conducted in the use of growth hormones and genetic therapies.

Prognosis

Prognosis of Osteogenesis Imperfecta
How well a person does depends on the type of OI they have.

1. Type I, or mild OI, is the most common form. Persons with this type can live a normal lifespan.
2. Type II is a severe form that is usually leads to death in the first year of life.
3. Type III is also called severe OI. Persons with this type have many fractures starting very early in life and can have severe bone deformities. Many become wheelchair bound and usually have a somewhat shortened life expectancy.
4. Type IV, or moderately severe OI, is similar to type I, although persons with type IV often need braces or crutches to walk. Life expectancy is normal or near normal.

Prevention

Prevention of Osteogenesis Imperfecta
Genetic counseling is recommended for couples considering pregnancy if there is a personal or family history of this condition.